Tuning instrument



Feb. 20, 1934. o. c. DEUTSCHER 1,947,584

TUNING -INSTRUMENT Filed March 5. 1931 2 Sheets-Sheet l lNvl-:NTOR 0504,@ C. DEUTSCHER BY/ @gwn/M ATTORNEY ""Feb. 20, 1934. o. c. DEUTSCHER 1,947,584

TUNING INSTRUMENT Filed March 3, 1951 2 Sheets-Sheet 2 056/12 c. @farsa/2 BY/@ZW ATTORNEY Patented Feb. 20, 1934 Oscar 0. Deutscher, Brooklyn,

Tv OFFICE 1,947,584 TUNING INSTRUMENT N. Y., assignor, by

mesne assignments, to Radio Corporation of America, New York, N.

Delaware Application March 3, 1931. Serial No. 519,766 11 Claims. (Cl. Z50- 40) This invention relates to variable tuning elements as used in connection with radio receiving apparatus and has as one of its objects to provide a straight line frequency condenser having an inductance coil concealed and protected within the structure.

A further feature is in the provision of a condenser formed primarily of two conical elements,

respectively iixed and movable,

by which an air l0 space between the adjacent surfaces of the cones is varied in direct proportion of the cones, whereby a greater pacity is obtainable than in condenser.

l5 Another purpose is to to the active area variation in caany other known produce a condenser o1' extreme simplicity, sensitiveness, compactness and efficiency, the same being actu which gives the entire range of one complete turn.

appear.

ated by a knob capacity during Other features and advantages will hereinafter In the accompanying drawings:-

ional view o! an ken on line l-l the same.

Figure 3 shows a longitudinal sectional view of a modication.

Throughout the several views v3Q designates in general a support,

the numeral such as a conventional panel, having rigidly attached by spacers 11, a bar 12, arranged in para side.

The bar 12 has secured 35 frame sides 13 connected by a llel at its inner at its ends a pair of plate bar 14 at their outer ends and constituting a rigid rectangular nonconducting frame.

The side members 13 are provided with central longitudinal slots 15 in which are slidably 4o contained two pairs of sleeves l 6 and 17 having flanges at each end to retain the bodies of the sleeves within the slots.

The pair of sleeves 16, adjacent the bar 12, carry conduction spindles 18, their reduced inner /43 portions supporting an insulating ring 19, conically recessed to receive the base 20, rmly seated therein and held of a metal cone by riveting the ends of the spindles 18 against its inner surface The other sleeves 17 contain ner another pair of conducting in a similar manspindles 22, re-

duced near their points to engage in a disc 23,

in which the smaller end of the and a series of perforations 24 55 the disc 23 admit air to the inte cone is fixed formed through rior of the cone.

Y., a corporation of Another cone 25 has a ilange 26 at its base which is rigidly secured to the inner side of the bar 12, to extend outwardly concentric with the cone 20.

A circular dielectric rod or tube 27 containing a hollow core 28 passes freely through the outer bar 12, axially of the cones and is provided with a fixed collar 29 impinging against the inner side of the disc 23, through which its reduced threaded portion 30 extends. Y n Y A clamp nut 31 draws the collar tightly to the disc and on the outer side of the nut is a yoke bar 32 rigidly held by a washer and clamp nut 33.

Attached at their ends respectively to the yoke bar 32, and plate bar 14, of the frame are a pair of coiled tension springs 84, the same acting to draw the cone 20 and its attachments outwardf ly away from the inner cone 2:5 to increase the air gap space 35 between the cones.

Connected by a joint 36 at the outer end of the tube 27, is a spindle36 having a coarse pitch spiral or thread 37 in its outer portion, in which operates a pin 38 xed in a sleeve39 solidly molded into a twirling knob 40 of conventional type.

The spindle 36 rotates within a lsecond sleeve 41 screw threaded at its end projecting through the panel 10 and drawn by a nut 42 to tighten its ange 43 against the outer end of hub44 formed on a circular index 45 to be held thereby closely against the :face of the panel.

The hub 44 contains an annular groove 46 into which enter the points of one or more screws 47 set in the knob 40 and by which it is held to rotate on the hub and index, a pointer 48 being provided on the knob to traverse the index. 1

As the pitch of the helixV 37 is designed to move the outer cone 20, the full limit of its travel at one 4complete revolution of the knob 40, it will be apparent that the superficial ,areas of the cones, as opposed one to the other, is under full control of an operator and that the air gap 35 will be varied directly in proportion to the active area 01' the cone surfaces involved.

It will be apparent that all looseness or back lash is eliminated due to the action of the springs 34, thereby rendering the device` instantly and fully responsive to any motion communicated to it by the knob 40.

In addition an inductance coil 49 is mounted on the tube 27 within the iixed cone 25 and in fixed relation to the movable cone 20, the coil being connected in the usual manner and is fully protected by being enclosed within the fixed cone.

Should an apparatus of greater capacity be desirable the cones may be used in multiple, as

'ipo

shown in Fig. 3, the structural features remaining substantially as described.

Thus a variable tuning apparatus of a straight line frequency of unusual merit has been disclosed in the preferred form of its embodiment, but it will be understood that minor changes in construction may be made without departing from the spirit and scope of the appended claims and that parts thereof may be used in place of the whole if found desirable.

Having thus described my invention and set forth the manner of its construction and application, what I claim as new and desire to` secure by Letters Patent, is: Y

1. A variable tuning circuitcomprising in combination, a variable condenser having telescopic hollow metallic frustums as electrodes, means for simultaneously varying the axial overlap of said frustrums and the gap between them to adjust the capacity with respect to displacement in accordance with a predetermined law,v and an inductance coil disposed entirely inside only one of said frustums, said coil being connected to said electrodes to provide said circuit.

2. In combination, in a tuned circui an inductance coil, and a substantially straight-linefrequency variable condenser having hollow telescopic cone-shaped electrodes electrically connected with said coil, said coil being entirely surg rounded by one of the electrodes.

fixed cone, means 3. A variable tuning circuit comprising a iixed hollow cone, a second hollow cone spacedly superposed thereover, a tube on which said second cone is mounted, said tube passing axially through the n for adjusting said tube longitudinally whereby the space between said cones may be varied, and an inductanceV coil on said tube within the xed cone, said coil being connected to said cones to provide said circuit.

4. A variable tuning circuit comprising an open frame, a rod slidably mounted in one member of the frame, means to adjust said rod lengthwise, a tension means for said rod, at least one hollow metallicY cone carried concentrically by said rod, at least one similar cone iixed in said frame intermediate the iirst named cone, and an inductance coil on said rod within the iiXed cone, said coil being connected to the cones to provide said circuit. A

5. A variable tuning circuit comprising an outer metallic cone, an inner metallic cone, means for axially displacing said outer cone with respect to said inner cone to thereby vary the capacity of said circuit, and an inductance coil mechanically associated with said last mentioned means, said coil being disposed within said inner cone and being entirely surrounded by said cone, and means for electrically connecting said coil to both said cones to provide said circuit.

6. A tuning unit comprising a stationary conical electrode, a movable conical electrode to cooperate with said stationary electrode to vary the capacity of said unit, and an inductance entirely surrounded by said stationary electrode, said inductance being electricallyconnected with both said electrodes.

'7. A tuning unit comprising a variable condenser having a manually operable electrode for tuning an electrical circuit, and an inductance coil in said circuit, said coil being mechanically associated with said manually operable electrode for movement therewith, and said condenser including a stationary electrode adapted to cooperate with said manually operable electrode, said coil being entirely surrounded by said stationary electrode. t

8. A variable tuning circuit comprising an outer metallic cone, an inner metallic cone, a rod means for axially displacing said outer cone with respect to said inner cone to thereby vary the capacity of said circuit, and an inductance coil on said last mentioned rod means, said coil being disposed within said inner cone and being entirely surrounded by said cone, and means for electrically connecting said coil to both said cones to provide said circuit.

9. A variable tuning circuit comprising an outer metallic cone, an inner metallic cone, a rod means for axially displacing said outer cone with respect to said inner cone to thereby vary the capacity of said circuit, and an inductance coil on said last mentioned rod means, said coil being disposed within said inner cone and being entirely surrounded by said cone, means for electrically connecting said coil to both said cones to provide said circuit and means for normally pulling said outer cone in a direction away from the inner cone.

10. A tuning unit comprising a stationary conical electrode, a movable conical electrode to cooperate with said stationary electrode to vary the capacity of said unit, a rod passing through said stationary electrode and afIiXed at one end to said movable electrode, and an inductance entirely surrounded by said stationary electrode, said inductance being electrically connected with both said electrodes.

11. A tuning unit comprisinga stationary conical electrode, a movable conical electrode to cooperate with said stationary electrode to vary the capacity of said unit, a rod passing through said stationary electrode and aiiixed at one end to said movable electrode, and an inductance coil mounted on the rod and being entirely surrounded by said stationary electrode, said inductance being electrically connected with both said electrodes.

OSCAR C. DEUTSCHER.

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